Implement DST calculation

5 files changed, 161 insertions, 82 deletions

diff --git a/src/fsm/common.c b/src/fsm/common.c
index 953a015..27c792f 100644
--- a/src/fsm/common.c
+++ b/src/fsm/common.c
@@ -1,7 +1,7 @@
 /*
  * The MIT License (MIT)
  *
- * Copyright (c) 2015 Matthias P. Braendli
+ * Copyright (c) 2016 Matthias P. Braendli
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -26,6 +26,7 @@
 #include "usart.h"
 #include "FreeRTOS.h"
 #include "timers.h"
+#include "gps.h"
 #include <stm32f4xx.h>
 #include <time.h>
 
@@ -38,6 +39,107 @@ static uint16_t lfsr;
 
 static void common_increase_timestamp(TimerHandle_t t);
 
+int find_last_sunday(const struct tm* time)
+{
+    struct tm t = *time;
+
+    // the last sunday can never be before the 20th
+    t.tm_mday = 20;
+
+    int last_sunday = 1;
+
+    while (t.tm_mon == time->tm_mon) {
+        t.tm_mday++;
+        if (mktime(&t) == (time_t)-1) {
+            // TODO error
+            return -1;
+        }
+
+        const int sunday = 0;
+        if (t.tm_wday == sunday) {
+            last_sunday = t.tm_mday;
+        }
+    }
+
+    return last_sunday;
+}
+
+/* Calculate if we are in daylight saving time.
+ * return  0 if false
+ *         1 if true
+ *        -1 in case of error
+ */
+static int is_dst(const struct tm *time)
+{
+    /* DST from 01:00 UTC on last Sunday in March
+     *     to   01:00 UTC on last Sunday in October
+     */
+    const int march = 2;
+    const int october = 9;
+    if (time->tm_mon < march) {
+        return 0;
+    }
+    else if (time->tm_mon == march) {
+        int last_sunday = find_last_sunday(time);
+        if (last_sunday == -1) return -1;
+
+        if (time->tm_mday < last_sunday) {
+            return 0;
+        }
+        else if (time->tm_mday == last_sunday) {
+            return (time->tm_hour < 1) ?  0 : 1;
+        }
+        else {
+            return 1;
+        }
+    }
+    else if (time->tm_mon > march && time->tm_mon < october) {
+        return 1;
+    }
+    else if (time->tm_mon == october) {
+        int last_sunday = find_last_sunday(time);
+        if (last_sunday == -1) return -1;
+
+        if (time->tm_mday < last_sunday) {
+            return 1;
+        }
+        else if (time->tm_mday == last_sunday) {
+            return (time->tm_hour < 1) ? 1 : 0;
+        }
+        else {
+            return 0;
+        }
+    }
+    else {
+        return 0;
+    }
+}
+
+int local_time(struct tm *time)
+{
+    const int local_time_offset=1; // hours
+
+    int valid = gps_utctime(time);
+
+    if (valid) {
+        time->tm_hour += local_time_offset;
+
+        if (is_dst(time)) {
+            time->tm_hour++;
+            time->tm_isdst = 1;
+        }
+
+        // Let mktime fix the struct tm *time
+        if (mktime(time) == (time_t)-1) {
+            // TODO inform about failure
+            valid = 0;
+        }
+    }
+
+    return valid;
+}
+
+
 void common_init(void)
 {
     common_timer = xTimerCreate("Timer",
@@ -62,21 +164,6 @@ uint64_t timestamp_now(void)
     return common_timestamp;
 }
 
-int dayofweek(uint8_t day, uint8_t month, uint16_t year)
-{
-   /* Zeller's congruence for the Gregorian calendar.
-    * With 0=Monday, ... 5=Saturday, 6=Sunday
-    */
-   if (month < 3) {
-      month += 12;
-      year--;
-   }
-   int k = year % 100;
-   int j = year / 100;
-   int h = day + 13*(month+1)/5 + k + k/4 + j/4 + 5*j;
-   return (h + 5) % 7 + 1;
-}
-
 
 // Return either 0 or 1, somewhat randomly
 int random_bool(void)
diff --git a/src/fsm/common.h b/src/fsm/common.h
index b283f03..80739cf 100644
--- a/src/fsm/common.h
+++ b/src/fsm/common.h
@@ -1,7 +1,7 @@
 /*
  * The MIT License (MIT)
  *
- * Copyright (c) 2015 Matthias P. Braendli
+ * Copyright (c) 2016 Matthias P. Braendli
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -26,31 +26,27 @@
  * a random number
  */
 
-#include <stdint.h>
+#pragma once
 
-#ifndef _COMMON_H_
-#define _COMMON_H_
+#include <stdint.h>
+#include <time.h>
 
 /* Feature defines */
 #define ENABLE_PSK31 0
 
 #define FLOAT_PI 3.1415926535897932384f
 
-
 void common_init(void);
 
 // Return the current timestamp in milliseconds. Timestamps are monotonic, and not
 // wall clock time.
 uint64_t timestamp_now(void);
 
-/* Convert date to day of week.
- * day:   1-31
- * month: 1-12
- * year:  1900 to 3000
- *
- * Returns 1=Monday, ... 6=Saturday, 7=Sunday
- */
-int dayofweek(uint8_t day, uint8_t month, uint16_t year);
+// Calculate local time from GPS time, including daylight saving time
+// Return 1 on success, 0 on failure
+// A call to this function will invalidate the information inside 'time'
+// regardless of return value.
+int local_time(struct tm *time);
 
 // Return either 0 or 1, somewhat randomly
 int random_bool(void);
@@ -62,5 +58,3 @@ int random_bool(void);
 #define FAULT_SOURCE_USART 4
 void trigger_fault(int source);
 
-#endif // _COMMON_H_
-
diff --git a/src/fsm/gps.c b/src/fsm/gps.c
index 7b86f1c..ea3e597 100644
--- a/src/fsm/gps.c
+++ b/src/fsm/gps.c
@@ -35,7 +35,8 @@
 
 
 TickType_t gps_timeutc_last_updated = 0;
-static struct gps_time_s gps_timeutc;
+static struct tm gps_timeutc;
+static int gps_timeutc_valid;
 
 const TickType_t gps_data_validity_timeout = 10000ul / portTICK_PERIOD_MS;
 
@@ -44,22 +45,23 @@ static void gps_task(void *pvParameters);
 SemaphoreHandle_t timeutc_semaphore;
 
 // Get current time from GPS
-void gps_utctime(struct gps_time_s *timeutc)
+int gps_utctime(struct tm *timeutc)
 {
+    int valid = 0;
+
     xSemaphoreTake(timeutc_semaphore, portMAX_DELAY);
     if (xTaskGetTickCount() - gps_timeutc_last_updated < gps_data_validity_timeout) {
-        timeutc->year  = gps_timeutc.year;
-        timeutc->month = gps_timeutc.month;
-        timeutc->day   = gps_timeutc.day;
-        timeutc->hour  = gps_timeutc.hour;
-        timeutc->min   = gps_timeutc.min;
-        timeutc->sec   = gps_timeutc.sec;
-        timeutc->valid = gps_timeutc.valid;
-    }
-    else {
-        timeutc->valid = 0;
+        timeutc->tm_year  = gps_timeutc.tm_year;
+        timeutc->tm_mon   = gps_timeutc.tm_mon;
+        timeutc->tm_mday  = gps_timeutc.tm_mday;
+        timeutc->tm_hour  = gps_timeutc.tm_hour;
+        timeutc->tm_min   = gps_timeutc.tm_min;
+        timeutc->tm_sec   = gps_timeutc.tm_sec;
+        valid             = gps_timeutc_valid;
     }
     xSemaphoreGive(timeutc_semaphore);
+
+    return valid;
 }
 
 #define RXBUF_LEN MAX_NMEA_SENTENCE_LEN
@@ -81,14 +83,14 @@ static void gps_task(void *pvParameters)
                         struct minmea_sentence_rmc frame;
                         if (minmea_parse_rmc(&frame, rxbuf)) {
                             xSemaphoreTake(timeutc_semaphore, portMAX_DELAY);
+                            gps_timeutc.tm_year  = 2000 + frame.date.year;
+                            gps_timeutc.tm_mon   = frame.date.month;
+                            gps_timeutc.tm_mday  = frame.date.day;
+                            gps_timeutc.tm_hour  = frame.time.hours;
+                            gps_timeutc.tm_min   = frame.time.minutes;
+                            gps_timeutc.tm_sec   = frame.time.seconds;
+                            gps_timeutc_valid    = frame.valid;
                             gps_timeutc_last_updated = xTaskGetTickCount();
-                            gps_timeutc.year  = 2000 + frame.date.year;
-                            gps_timeutc.month = frame.date.month;
-                            gps_timeutc.day   = frame.date.day;
-                            gps_timeutc.hour  = frame.time.hours;
-                            gps_timeutc.min   = frame.time.minutes;
-                            gps_timeutc.sec   = frame.time.seconds;
-                            gps_timeutc.valid = frame.valid;
                             xSemaphoreGive(timeutc_semaphore);
                         }
                     } break;
@@ -101,7 +103,7 @@ static void gps_task(void *pvParameters)
 
 void gps_init()
 {
-    gps_timeutc.valid = 0;
+    gps_timeutc_valid = 0;
 
     usart_gps_init();
 
@@ -127,7 +129,7 @@ void gps_init()
 int gps_locked()
 {
     if (xTaskGetTickCount() - gps_timeutc_last_updated < gps_data_validity_timeout) {
-        return gps_timeutc.valid;
+        return gps_timeutc_valid;
     }
     else {
         return 0;
diff --git a/src/fsm/gps.h b/src/fsm/gps.h
index b1f023a..3472237 100644
--- a/src/fsm/gps.h
+++ b/src/fsm/gps.h
@@ -22,10 +22,10 @@
  * SOFTWARE.
 */
 
-#include <stdint.h>
+#pragma once
 
-#ifndef __GPS_H_
-#define __GPS_H_
+#include <stdint.h>
+#include <time.h>
 
 /* Setup GPS receiver over USART and parse time */
 
@@ -34,16 +34,6 @@
  * board RX to GPS TX on PD9
  */
 
-struct gps_time_s {
-    uint16_t  year;   // Year, range 1999..2099 (UTC)
-    uint8_t   month;  // Month, range 1..12 (UTC)
-    uint8_t   day;    // Day of Month, range 1..31 (UTC)
-    uint8_t   hour;   // Hour of Day, range 0..23 (UTC)
-    uint8_t   min;    // Minute of Hour, range 0..59 (UTC)
-    uint8_t   sec;    // Seconds of Minute, range 0..59 (UTC)
-    uint8_t   valid;  // validity flag
-};
-
 // Setup communication and GPS receiver
 void gps_init();
 
@@ -51,7 +41,6 @@ void gps_init();
 int gps_locked();
 
 // Get current time from GPS
-void gps_utctime(struct gps_time_s *timeutc);
-
-#endif // __GPS_H_
+// Returns 1 if time is valid, 0 otherwise
+int gps_utctime(struct tm *timeutc);
 
diff --git a/src/fsm/main.c b/src/fsm/main.c
index 94c15e0..1376b4b 100644
--- a/src/fsm/main.c
+++ b/src/fsm/main.c
@@ -266,7 +266,7 @@ static void audio_callback(void* context, int select_buffer)
     ProvideAudioBufferWithoutBlocking(samples, samples_len);
 }
 
-static struct gps_time_s gps_time;
+static struct tm gps_time;
 static void gps_monit_task(void *pvParameters)
 {
     GPIO_SetBits(GPIOD, GPIOD_BOARD_LED_BLUE);
@@ -274,27 +274,34 @@ static void gps_monit_task(void *pvParameters)
     int t_gps_print_latch = 0;
 
     while (1) {
-        if (gps_locked()) {
+        struct tm time;
+        int time_valid = local_time(&time);
 
-            gps_utctime(&gps_time);
-
-            if (gps_time.sec % 4 >= 2) {
+        if (time_valid) {
+            if (time.tm_sec % 4 >= 2) {
                 GPIO_SetBits(GPIOD, GPIOD_BOARD_LED_BLUE);
             }
             else {
                 GPIO_ResetBits(GPIOD, GPIOD_BOARD_LED_BLUE);
             }
 
-            if (gps_time.sec % 30 == 0 && t_gps_print_latch == 0) {
-                usart_debug("T_GPS %04d-%02d-%02d %02d:%02d:%02d\r\n",
-                        gps_time.year, gps_time.month, gps_time.day,
-                        gps_time.hour, gps_time.min, gps_time.sec);
+        }
 
-                t_gps_print_latch = 1;
-            }
-            if (gps_time.sec % 30 > 0) {
-                t_gps_print_latch = 0;
-            }
+        gps_utctime(&gps_time);
+
+        if (gps_time.tm_sec % 30 == 0 && t_gps_print_latch == 0) {
+            usart_debug("T_GPS %04d-%02d-%02d %02d:%02d:%02d\r\n",
+                    gps_time.tm_year, gps_time.tm_mon, gps_time.tm_mday,
+                    gps_time.tm_hour, gps_time.tm_min, gps_time.tm_sec);
+
+            usart_debug("TIME  %04d-%02d-%02d %02d:%02d:%02d\r\n",
+                    time.tm_year, time.tm_mon, time.tm_mday,
+                    time.tm_hour, time.tm_min, time.tm_sec);
+
+            t_gps_print_latch = 1;
+        }
+        if (gps_time.tm_sec % 30 > 0) {
+            t_gps_print_latch = 0;
         }
 
         vTaskDelay(100 / portTICK_RATE_MS);